Its impossible to fit everything in one book, i'm sure you'll agree.
So its easier to use an event, to display a point. Like how public opinion can bring about change - and public health. Rise of Facism - Hitler. etc etc
Although history books are always biased, so its pointless whining over it - its best to just stock up on as much stuff as possible, and as wide a range as possible. Don't let one book dictate your life.
Captain Blackadder: You see, Baldrick, in order to prevent war two great super-armies developed. Us, the Russians and the French on one side, Germany and Austro-Hungary on the other. The idea being that each army would act as the other's deterrent. That way, there could never be a war.
Private Baldrick: Except, this is sort of a war, isn't it?
Captain Blackadder: That's right. There was one tiny flaw in the plan.
Lieutenant George: O, what was that?
Captain Blackadder: It was bollocks.